(1) Field of the Invention
The present invention relates to a method and apparatus for forming a film coating on the surface of a base. More specifically, the present invention relates to an improved method and apparatus for forming a clear transparent electrically conductive film or a clear transparent insulated coating on the surface of a base.
(2) Description of the Prior Art
The prior art has disclosed methods for forming coatings or foils made of stannic oxide, indium oxide, or foils and coatings of similar materials. One of the methods disclosed within the prior art is a vacuum vapor deposition method. The vacuum vapor deposition method known in the prior art cannot be applied continuously and onto a wide area due to the fact that the vacuum vapor deposition system must be a closed system. The coatings obtained by the vapor deposition according to the prior art are not only expensive but small and are limited in their use within the electronics field, optical field, and/or other fields where such coatings are useful.
In light of the limitations of the prior art vacuum deposition method as pointed out above, there has existed a need for a coating having excellent light transmittance comparable with one obtained by vacuum vapor deposition and also having excellent crystallinity, thermal stability, weather proofing property, chemical proofing property, adhesion power and mechanical strength. The prior art is also lacking in that it is not capable of producing a coating having the qualities as described above in a continuous manner onto a large base surface.
A method exists within the prior art for forming a coating spread on a wide area of a base surface. This method is a chemical method in which a gas containing a film forming component is sprayed onto a heated surface of a base sheet. However, according to this method, the thickness of the coating cannot be closely controlled. Furthermore, the resulting coating does not have a desirable surface uniformity. Furthermore, the surface of the coating formed according to this method has an undesirable appearance caused by an unavoidable white cloudiness in the coating. This white cloudiness damages the electro-optical properties and therefore this method is not utilized within the field of electronics.